Electrical rotary joint

ABSTRACT

A rotary electrical joint consisting of at least one, and preferably two, rotary electrical contacts adapted to be secured to a rotating member, and at least one, preferably two, oscillating electrical contacts mounted for movement to and fro in an arc about the axis of rotation of the rotary contacts. The oscillating contacts are held in electrical engagement with the rotary contacts during at least a portion of one revolution of the rotary contacts. Circuit breaker means is provided to cyclically disengage the contacts at predetermined intervals during the rotation of the rotary contact and return drive means is provided to drive the oscillating contact in the opposite direction to the rotation of the rotary contact when the contacts are disengaged.

United States Patent Groskopfs [4 1 May 16, 1972 [s41 ELECTRICAL ROTARYJOINT 3,138,672 6/1964 Shlesinger ..200/11 R [72} Inventor: Ernestcroskopfs Caledon East Ontario, 3,482,071 12/1969 Mlller ..200/ l6 ACanada 7 Primary Examiner-J. R. Scott [73] Assignee: Spar AerospaceProducts Limited, Toronto y h r t nhaugh & C0-

lnternational Airport, Ontario, Canada [57 BSTRACT A [22] Filed: Dec.1,1970 1 A rotary electrical joint consisting of at least one. and [21]PP 93,938 preferably two, rotary electrical contacts adapted to besecured to a rotating member. and at least one, preferably 52 US. 01..200/11 R ZOO/16A 200/18 tw1scillating electrical contacts mounted formovement 260/153 and fro in an are about the axis of rotation of therotary con- 51 mm .L ..H0lh 19/54 HOlh 27/76 The mating are held ineltctrical engage- [58] Field of'earch "200/1 1 R A 17 18 23 ment withthe rotary contacts during at least a portion of one 7 11 R 11 3l0/24'5revolution of the rotary contacts. Circuit breaker means is provided tocyclically disengage the contacts at predetermined intervals during therotation of the rotary contact and [56] References cued return drivemeans is provided to drive the oscillating contact UNITED STATES PATENTSin the opposite direction to the rotation of the rotary contact when thecontacts are disengaged. 3,504,141 3/1970 Webster ..200/25 1,995,708 3/1935 Fischer ..200/ll R" 20 Claims,7Drawing Figures 43 H 44 I i 36 2O 9082 8 4 {11 1 I1 Q /s nli 1: i4 72- K 68-1 1. 1 gz-s 1 4- 12-? i 60 1 60"4 32 54 I 5762 88 I 72% so 86 90 W 1 -4 6 74 I II [I 4 4 Sheets-Sheet lPatented May 16, 1972 INVENTOR. ERNEST GROSKOPFS FIG'G ATTORNEYSPatented May 16, 1972 3,663,770

4 Sheets-Sheet 2 INVENTOR. ERNEST GROSKOPFS ATTORNEYS Patented May 16,1972 4 Sheets-Sheet 3 I N VENT JP v E RN E ST GROSKOPFS ATTORNEYSPatented May 16, 1972 3,663,770

4 Sheets-Sheet 4 [.N'Vfi. 1 0r" ERNEST GROSKOPF'S Mai/1& f

ATTORNEYS ELECTRICAL ROTARY JOINT FIELD OF INVENTION This inventionrelates to rotary electrical joints. In particu-. lar, the inventionrelates to a rotary connected joint for connecting two componentssurmounted for rotation relative to one another so as to provideelectrical contact between the components. I

PRIOR ART In the known rotary electrical joints, the common practice isto provide a slip-ring type of connection between the two rotatingmembers so that electrical power can be transferred from one member toanother. It will be understood that the two rotating bodies cannot beconnected, by conventional electrical wiring as the wiring would becometwisted as the bodies rotate relative to one another. The difiicultywiththe conventional slip-ring type of joint is that it is subject towear and, in some instances, considerable power is required in order toovercome the frictional resistance to rotation of the slip'rings. Inaddition, the slippingaction is not a satisfactory method oftransferring electrical signals in that it can create radio noiseinterference.

One of the areas in which a rotary electrical joint is required is inthe field of space communications. The slip-ring type of electricaljoint is unsatisfactory for use in spacecraft for the reasons mentionedabove. The problems associated with wear and power consumption of theslip-ring joint become more acute in use in spacecraft applications.Rotary electrical joints are required in spacecraft in order to connectthe space capsule to solar cells which are mounted on solar panels whichextend outwardly from the spacecraft. To be effective, the solar panelsmust be oriented to face the sun and when a spacecraft is in orbit, itis necessary to maintain a substantially continuous rotation of thesolar panels relative to the spacecraft.

The wear problems associated with the conventional slipring joints havebeen eliminated by the joint of the present invention due to the factthat the electrical contacts do not slip continuously relative to oneanother and, as shown in the preferred embodiment described hereinafter,the electrical contacts are maintained in a spaced relationship duringthe recycling operation. 7

The joint of the present invention employs at least two sets ofcontacts, one contact of each set being electrically connected to oneanother of the relatively rotating bodies and the recycling of each setof contacts is carried out while the other set of contacts are inelectrical engagement such that there is no interruption in the flow ofelectrical power or signals between the rotating components.

The rotary electrical joint of the present invention is alsodistinguished by a number of novel structural features which contributeto the successful operation of the joint. These structural featuresinclude the locking arrangement which locks each pair of contacts toprevent rotation of one contact relative to the other when engagementwith one another, and a compression spring which serves to maintain theelectrical contacts in engagement with one another while locked.-lnaddition the coil spring structure which connects the oscillatingcontacts to the stationary housing also serves to provide a path forconductors extending between the oscillating contacts and the stationaryhousing.

SUMMARY The present invention overcomes thedifficulties of the prior artdescribed above and provides a rotary electrical joint which is adaptedto maintain continuous electrical contact between two relativelyrotating bodies without permitting the electrical wiring of either ofthe two bodies to become excessively twisted as a result of the rotationof one body relative to the other. According to an embodiment of thepresent invention, this desirable objective is achieved by providing arotary electrical joint comprising at least two rotary electricalcontact means adapted to be secured to a rotating member for rotationtherewith about an axis and at least two oscillating electrical contactmeans mounted for movement to and fro in a predetermined arc about saidaxis independently of one another to cooperate with the rotary contactsto provide at least two pairs of complementary contacts, each consistingof a rotary contact and an oscillating contact. Means are also providedfor maintaining each pair of contacts in electrical engagement during atleast a portion of one revolution of the rotary contacts. Circuitbreaker means are provided for cyclically disengaging one pair ofcontacts while the other pair remains in contact. Return drive means isprovided to drive each of the oscillating contact means in a directionopposite to the direction of rotation of the rotary contact means whenthe oscillating contact is disengaged from the rotary contact by thecircuit breaker means.

The invention will be more clearly understood after reference to thefollowing detailed specification read in conjunction with the drawings.

FIG. 1 is a pictorial view of a diagrammatic illustration of a rotaryjoint without many of the structural elements of an actual joint;

FIG. 2 is a longitudinal sectional view of a rotary electrical jointaccording to an embodiment of the present invention;

FIG. 3 is a cross-sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 2;

FIG. 5 is a partially sectional view of a portion of a contact structureof FIG. 2;

FIG. 6 is a small pictorial view of a space vehicle of a type with whichthe joints of this invention may be used; and

FIG. 7 is a cross-sectional view of a joint of the type having only oneset of contacts.

As indicated above, FIG. 1 of the drawings is not intended to illustratea completely operable structure but rather it serves to illustrate theprinciple of operation of a rotary electrical joint according toanembodiment of the present invention. The joint is collectivelyidentified by the reference numeral l0.

The reference numeral 12 refers generally to the upper set ofcomplementary contacts and the reference numeral 14 refers generally'tothe lower set of complementary contacts. Each set of contacts consistsof a rotary contact assembly 16 and an oscillating contact assembly 18.Each of the rotary assemblies 16 are adapted to be secured to a rotaryshaft 20. The assemblies 16 are also free to reciprocate longitudinallyrelative to the shaft 20 in the direction of the arrows A.

The oscillating assemblies 18 are mounted for rotation relative to theshaft 20 by means of suitable ball bearing races 22. As will be seenhereinafter, the oscillating assemblies are also secured to a body whichdoes not rotate with the shaft 20 by a suitable return drive means. Inaddition, each of the oscillating assemblies 18 is urged into engagementwith the rotary assembly 16 by a suitable coil spring, as will bedescribed hereinafter, and the assemblies are locked in engagement whenthey are in electrical contact.

Each of the assemblies 16 has a cam track surface 24 formed adjacent theperipheral edge thereof and having outwardly protruding sections 26 atspaced intervals about the periphery thereof. A number of cam rollers 28are mounted for rotation on shafts 30 which are fixed relative to astationary component. The cam rollers 28 are located so as to bearagainst the cam surfaces 24. Theprojections 26 of the cam surfaces ofone rotary assembly are circumferentially spaced relative to theprojections 20 of the other rotary assembly such that the cam rollerswill not engage the projections of both cam surfaces simultaneously. Inuse, the shaft 20 rotates carrying with it the rotary assemblies 16 andthe oscillating assemblies comes in contact with the rollers 28, therotary assembly 26 is displaced longitudinally relative to the shaft 20.The longitudinal displacement of the rotary assembly 16 serves torelease the locking rings which secures the rotary assembly and oscil-18. When the cam surface 26 of one rotary assembly I lating assembly toone another when in electrical engagement. The return drive means thenserves to reverse the direction of rotation of the oscillating assemblyso as to return it to a predetermined fixed position relative to thestationary housing. During the time that one set of contacts is out ofengagement, the other set remains in engagement. The second set ofcontacts will be disengaged when the protrusion 26 of the cam surface ofthe second set engages the roller 28 by which time the first set will beagain locked in contact. When in use, as will be described hereinafter,the rotary assembly is electrically connected to electrical wiringextending through the hollow tube 20 while the oscillating assembly isconnected to electrical wiring carried by a stationary housing or thelike. The wiring connecting the oscillating assembly and the stationaryhousing does not become excessively wound during the rotational movementof the oscillating assembly and the extent of movement of theoscillating assembly can be limited by increasing the number ofprotrusions formed on the cam surface so that the direction of rotationof the oscillating assembly may be altered several times in the courseof a single revolution of the shaft 20.

Referring now to FIG. 2 of the drawing, the reference numeral againrefers to a rotary electrical joint according to an embodiment of thisinvention. The joint 10 is used to connect a rotating component 40 and astationary component 42. The joint comprises a housing generallyidentified by the reference numeral 32. The housing 32 consists of atubular side wall 34 and a pair of transversely extending end walls 36.One of the end walls 36 has a flange adapted to be secured to thestationary component 42.

The hollow shaft is connected to the rotating component 40 for rotationabout the axis of the component. The junction 43 is carried by an endplate 44 which is clamped between the rotary component 40 and the shaft20. The junction 43 is adapted to be connected to a conduit 44 which iselectrically connected to the rotating component.

A pair of sleeves 46 are located towards opposite ends of the shaft 20to support ball bearings 48 which serve to rotatably mount the shaft 20in the end walls 36 of the housing so that the shaft 20 is free torotate within the housing. A second pair of sleeves 50 are located onthe shaft 20 inwardly from the first mentioned sleeves 46 as shown inFIG. 2. These sleeves provide a support for the oscillating assembly andcompression spring as will be described hereinafter.

As previously indicated with reference to FIG. 1, the joint includes twosets of contacts 12 and 14. The sets of contacts are identical to oneanother and consequently only one set will be described hereinafter.

As previously indicated, the set of contacts 12 comprises a rotaryassembly 16 and an oscillating assembly 18. The rotary assembly 16comprises a rotary contact support disc 52 which has a centralpassageway defined by an upwardly extending tubular portion 54. A pairof key ends 56 project inwardly from the support 52 through elongatedpassages formed in the sleeve 50 into elongated slots 58 formed in theshaft 20. The sleeve portion 56 is of'a sufficient diameter to fit in aclose fitting sliding relationship over the sleeve 50 and the pin 56 isof a diameter to fit in a close fitting relationship within the slot 58so as to permit longitudinal movement of the rotary assembly 16 relativeto the shaft while rotatably driving the rotary assembly 16 with theshaft in use.

A coil spring 60 extends around the sleeve 50 and has one end located ina slot formed in the sleeve 50 and the other end located in the slotformed in the end of the sleeve portion 54 of the support 52. Theimmersion spring 60 serves to urge the rotary assembly 16 intoengagement with the oscillating assembly 18 as will be describedhereinafter.

The rotary assembly has a plurality of annular contact sup port rings 62rotated at the peripheral edge of the support 54 and mounted one on topof the other. A plurality of rotary electrical contacts 64 projectradially inwardly into the contact chamber 66 formed inwardly of therings 62. The rings 62 are clamped together by clamping screws 68 whichare threadably mounted in the support 52. A number of latch elements 70are secured to the rotary assemblies by the mounting screw 68 so as toproject inwardly therefrom to lock with the oscillating assembly as willbe described hereinafter.

Each of the oscillating assemblies 18 comprises a support disc 72 whichis rotatably mounted relative to the sleeve 50 by means of a ballbearing race 74. From FIG. 2 of the drawings, it will be seen that whilethe oscillating support 72 is mounted for rotation relative to the shaft20, it is fixed against longitudinal movement relative to the shaft 20.A plurality of oscillating contact support rings 76 are mounted one ontop of the other and serve to support oscillating contacts 78, whichproject radially outwardly into the contact chamber 66 formed betweenthe rotary contact assembly and the shaft. A plurality of notches 80 arelocated on an outwardly projecting flange portion of each oscillatingassembly. The notches 80 are adapted to receive the latch members 70 ofthe rotary assemblies 16.

As shown with reference to FIGS. 2 and 4 of the drawings, each of theoscillating assemblies is connected to the housing 32 by means of a coilspring 82. The inner end of the coil spring 82 is connected to theoscillating assembly 18 and the outer end of the coil spring isconnected to the housing 32 in a manner such that when the shaft rotatesin its operative direction of rotation, the coil spring is tightenedsuch that the forces applied by the coil spring act in a directionopposite to the direction of rotation of the shaft 20.

Referring now to FIGS. 1, 2 and 3 of the drawings, it will be seen thatthe cam surface 24 extends around the periphery of the under side of therotary assembly 16 and has three projections 26 extending outwardlytherefrom. The projections 26 are spaced at 120 intervals about theperipheral edge. Three cam rollers 28 are mounted on three supportshafts 30 which project inwardly from the housing 32 at 120 intervals.The shafts 30 are mounted on threaded supports 84 which are located inside passageways formed in the housing 32 so as to support the camrollers in a fixed position relative to the housing. One rotary housing16 is located relative to the other rotary housing such that theprotrusions 26 of one are out of alignment with the protrusions 26 ofthe other so that the cam rollers will move the rotary assemblies out ofcontact with their oscillating assemblies at different times during therotation about the axis ofthe shaft.

A stationary junction 42a is supported by a support bracket 86 in aposition overlying the output passage 88 of the housing 32 so as toprovide a junction for connection to a conduit 43a which is inelectrical contact with the stationary component.

In the embodiment illustrated in FIG. 2, electrical wires 90 extend fromthe junction 43 to each of the oscillating assemblies so as to provideone wire in electrical connection with each of the electrical contactsof the oscilating assembly as shown at 92 in FIG. 2. The wires 90 aresecured to the coil spring 82 so as to extend from their fixed positionrelative to the housing to the oscillating assembly. By arranging thewires in this manner, it is possible to permit the oscillating housingto move to and fro while controlling the movement of the connectingwires in such a way that they do not become entangled. It will beunderstood that in certain instances where only one conductor isrequired, the coil spring itself may act as a conductor withoutrequiring additional wiring.

Fixed electrical wires 94 extend from the junction 422 into the hollowcenter of the shaft 20 to branch out through passages 96 formed in theshaft to extend into the'chamber formed between the shaft and the wallof the housing. The wires 94 are then formed to extend through passages98 formed in the annular portion of the rotary support assembly. Thewires 94 are then connected to a contact 64 of the rotary assembly 16.In the embodiment illustrated in FIG. 2 of the drawings, all of theingoing electrical wires 94 are secured to a contact ring of the lowerof the two rotary assemblies. Contact between the electrical contacts ofone rotary assembly and the other rotary assembly is achieved by sixelectrical wires 100 which extend from one contact to the other throughpassageways 102 formed in the rotary assemblies.

. In order to control the extent of recycling of the oscillating contactassemblies when the locking mechanism is disengaged, a pin 83 is mountedon the upper edge 85 of the oscillating assembly (FIG. 5) and a smallblock 87 projects from the end wall 36 into the path of rotation of thepin 83. When the locking mechanism is released and the spring mechanismdrives the oscillating housing in the direction of the arrow D, therotational drive of the spring will continue until the pin 83 strikes alug 87.

When the joint illustrated in FIG. 1 is in use, the drive shaft isrotatably driven by the drive means (not shown) which drives therotating component 40 relative to the stationary component 42. Whereasin the embodiment shown in FIG. 1 the shaft is an integral part of therotating component, the device of FIG. 2 has its own shaft which isconnected to the shaft of the component. When the joint is in theposition shown in FIG. 2, the upper set of contacts are in electricalengagement with one another and the latch 70 is operably located withinthe slot 80 so that the upper set of contacts are locked in engagementfor rotation with the shaft 20. The lower set of contacts 14 are out ofengagement due to the fact that the cam roller is at a point engagingthe outwardly projecting portion of the cam track of the lower rotaryassembly. When the lower assembly is in this disengaged position, thespring 82 serves to reverse the direction of rotation of the oscillatingmember so as to return it to a fixed position relative to the housing.When the oscillating assembly is returned to fixed position, thecompression spring 60 urges the latch 70 into engagement with the nextadjacent notch 80.

Further rotation of the shaft 20 will again tighten the spiral springs82 until the protruding portion of the upper rotary cam comes intocontact with a roller 28. The cam roller will elevate the rotaryassembly so as to permit the oscillating assembly to return to its fixedposition relative to the housing under the influence of the spiralspring 80. This procedure will be repeated at 120 intervals of rotationfor each set of contacts.

An uninterrupted flow of current is achieved by connecting the rotaryjunction 42 to one of the rotary contact assemblies and by electricallyconnecting one rotary assembly to the other rotary assembly such thatwhen one or other of the contacts is broken by the camming action,current will pass through the contacts which are unbroken.

While a number of the structural features of the embodiment disclosed inFIG. 2 are not essential to the operation of a joint according to thebroad principles of this device, they do nevertheless contributesubstantially to the practical value of the device. For example, thearrangement wherein the contacts are stacked one on top of the otherwith the oscillating contacts arranged within the contact chamber formedin the rotary contact assembly provides a very efficient use of thespace provided within the housing, and it also permits a large number ofcontacts to be located within a limited space. In addition, the use ofthe latch and a complementary slot ensures that the contacts will beheld out of contact by the action of the underside of the latch bearingagainst the upper surface of the oscillating contact during therecycling of the oscillating contact. This structure does not allow theelectrical contacts to slide relative to one another so that frictionalwear and radio noise as a result of the slipping of the contacts iseliminated. In addition, the spiral springs serve to provide convenientpaths for the conductor wires and by securing the wires to the spiralsprings by means of an adhesive, it is possible to permit the wires toflex in use while holding them in a controlled configuration.

These and other advantages of the structure of FIG. 1 will be apparentto those skilled in the art.

From the foregoing, it will be apparent that the present inventionprovides a simple and effective rotary electrical joint suitable for usein connecting the flat panels which support the solar cells of aspacecraft in use. Due to the fact that .the connection is maintainedcontinuously and recycling takes place without requiring recycling ofthe shaft 20, it is possible to provide a continuous electricalconnection between the solar cells and the spacecraft. The fact that theonly structural component which has to be recycled is the oscillatingcontact, it is of considerable advantage in a spacecraft application asthis eliminates the necessity of providing any mechanical drive meansfor rotatably driving the panels, in a direction opposite to theirnormal driven direction of rotation. Considerably less power is requiredin order to recycle the relatively small oscillating contacts than wouldbe required in order to recycle the large flat panels which extendoutwardly from a spacecraft. FIG. 6 of the drawings shows a typicalspacecraft installation wherein the electrical joint may be used toconnect the panel supporting shafts 1 10 to the spacecraft 112.

An alternative form of switch is illustrated in FIG. 7 of the drawings.In this drawing, the reference numerals correspond to the referencenumerals used to identify like parts in FIG. 2 of the drawings. In thisembodiment of the invention, there, is only one set of contacts whichare identified by the reference numeral 12. The difference between theoperation of this device and that illustrated in FIG. 2 is that when thecontacts open, the flow of current from the rotating body to thestationary body will be interrupted. There are certain applications inwhich this type of interruption is not a serious drawback.

Various modifications of the illustrated apparatus will be apparent tothose skilled in the art without departing from the scope of thisinvention. For example, the contacts may be made in the form of taperedring contacts so as to mechani cally engage one another in a lockedarrangement by reason of the interlocking tapers.

In a further modification, the complementary contacts may be in the formof a pair of fiat discs with a plurality of annular rings of contactsrather than the stacked contact assembly illustrated in FIG. 2.

What I claim as my invention is:

l. A rotary electrical joint comprising:

a. at least one rotary electrical contact means adapted to be secured toa rotating member for rotation therewith about an axis,

b. at least one oscillating electrical contact means mounted formovement to and fro in a predetermined arc about said axis to cooperatewith said rotary contact to provide at least one pair of complementarycontacts consisting of a rotary contact and an oscillating contact,

c. means for maintaining said pair of complementary contacts inelectrical engagement during at least a portion of one revolution ofsaid rotary contacts,

d. circuit breaker means for cyclically disengaging said complementarycontacts,

e. return drive means driving said oscillating contact means in adirection opposite to the direction of rotation of said rotary contactmeans when disengaged from said rotary contact means by said circuitbreaker means, and

f. releasable locking means for mechanically locking said complementatycontacts to one another to prevent slipping between the rotary andoscillating contacts, said locking means being released by said circuitbreaker when said complementary contacts are disengaged to permit thereturn drive means to operate.

2. A rotary electrical joint comprising:

a. at least two rotary electrical contact means adapted to be secured toa rotating member for rotation therewith about an axis,

b. at least two oscillating electrical contact means mounted formovement to and fro in a predetermined are about said axis independentlyof one another to cooperate with said rotary contacts to provide atleast two pairs of complementary contacts, each consisting of a rotarycontact and an oscillating contact,

c. means for maintaining each pair of contacts in electrical engagementduring at least a portion of one revolution of said rotary contacts,

d. circuit breaker means for cyclically disengaging one pair of contactswhile the other pair remains in contact and the second mentioned pair ofcontacts while the first mentioned pair of contacts remain in contact,

e. return drive means for independently driving each of said oscillatingcontact means in a direction opposite to the direction of rotation ofsaid rotary contact means when disengaged from said rotary contact meansby said circuit breaker means, and

f. releasable locking means for mechanically locking the contacts ofeach pair of complementary contacts relative to one another to preventrotary slipping between the retary contact and the oscillating contactof each pair, said locking means being releasable by said circuitbreaker means when said complementary contacts of each pair of contactsare disengaged to permit the return drive means to operate.

3. A rotary electrical joint for connecting two components, one of whichis to be mounted for rotation relative to the other, comprising:

a. a housing adapted to be secured to one of said components,

b, a chamber formed in said housing,

c. a hollow shaft rotatably mounted in said housing and extending intosaid chamber for rotation about a longitudinally extending axis,

. at least two rotary contact assemblies mounted for rotation on saidshaft and spaced longitudinally relative to one another within saidchamber,

e. at least two oscillating electrical contact means mounted formovement to and fro within said housing relative to said shaft in apredetermined are about said axis independently of one another, saidoscillating contacts cooperating with said rotary contacts to provide atleast two pairs of complementary contacts each consisting of a rotarycontact and an oscillating contact, means for maintaining each pair ofcontacts in electrical engagement during at least a portion of onerevolution of said rotary contacts,

f. circuit breaker means for cyclically disengaging one pair of contactswhile the other pair remains in contact and the second pair of contactswhile the first mentioned pair of contacts remain in contact,

return drive means for independently driving each of said oscillatingcontact means in a direction opposite to the direction of rotation ofsaid rotary contact means when disengaged from said rotary contact meansby said circuit breaker means, and

. releasable locking means for mechanically locking the contacts of eachpair of complementary contacts relative to one another to prevent rotaryslipping between the rotary contact and the oscillating contact of eachpair, said locking means being releasable by said circuit breaker meanswhen said complementary contacts of each pair of contacts are disengagedto permit the return drive means to operate.

4. A rotary electrical joint as claimed in claim 3 wherein saidreleasable locking means comprises latch means carried by each of saidrotary contacts and complementary slot means formed in each of saidoscillating contacts, said means for maintaining each pair of contactsin electrical engagement serving to urge said latch means intoengagement with said slot means.

5. A rotary electrical joint as claimed in claim 3 wherein said meansfor maintaining each pair of contacts in electrical engagement comprisesa pair of compression springs mounted coaxially with said shaft andreacting between said shaft and each of said electrical contact means.

6. A rotary electrical joint as claimed in claim 3 wherein said returndrive means comprises coil spring means connecting each of saidoscillating contact means to said housing, said coil spring means beingbiased to rotatably drive said oscillating assemblies in said directionopposite to the direction of rotation of the rotary contact means.

7. A rotary electrical joint as claimed in claim 6 including stop meanscoacting between said housing and each of said oscillating contact meansto limit the rotation of said oscillating contact means in the directionof rotation of said coil spring bias.

8. A rotary joint as claimed in claim 3 wherein each of said rotarycontact means is in the form of a contact assembly comprising:

a. a rotary contact support disc having a central passage therein toreceive said shaft, said disc being keyed to said shaft for longitudinalmovement relative to said shaft and rotation with said shaft,

a plurality of contact support rings mounted adjacent the outerperipheral edge of said rotary disc and arranged one on top of the otherin a direction towards the opposite ends of said housing, said rotarycontact support rings having inner peripheral edges spaced radiallyoutwardly from said shaft to form an annular contact chambertherebetween,

. rotary electrical contacts extending radially inwardly from each ofsaid rotary contact supportrings into said contact chamber, each of saidoscillating electrical contact means consisting of an assemblycomprising,

an oscillating contact support disc mounted on said shaft for rotationrelative to said shaft about said axis and secured against longitudinalmovement relative to said shaft,

e. a plurality of oscillating support rings mounted on said oscillatingsupport disc and extending longitudinally inwardly of said housing andoscillating electrical contacts extending radially outwardly from eachof said oscillating contact support rings, each of said oscillatingcontact assemblies being mounted for rotation about said shaft with saidoscillating contact support rings extending into a contact chamber of arotary contact assembly such that the radially extending electricalcontacts of the rotary assembly and the radially extending electricalcontacts of the oscillating assembly overlap one another.

9. A rotary joint as claimed in claim 8 wherein said circuit breakermeans comprises:

a. at least one cam roller mounted for rotation about a transverse axisand fixed to said housing to extend into said chamber,

b. each of said rotary support discs having an annular cam track surfaceextending inwardly from the peripheral edge thereof, said cam surfacesoverlying said cam roller means and having at least one protrudingsection extending outwardly from the plane of the remainder of the camsurface, the protruding sections of one cam surface beingcircumferentially spaced relative to the protruding sections of theother cam surface such that said cam roller will displace one of saidrotary contact members longitudinally out of contact with itscomplementary oscillating assembly when one of said protruding sectionsof said cam surface engages said roller means, and the other rotarycontact will be moved out of engagement with the other oscillatingassembly when the protruding sections of the cam surface of the otherrotary assembly is engaged by said cam means such that one or other ofthe rotary assemblies will at all times remain in contact with anoscillating assembly.

10. A rotary joint as claimed in claim 3 including electrical conductormeans for electrically connecting each of the electrical contact meansof one of the rotary contacts with an electrical contact means of theother rotary contact.

11. A rotary joint as claimed in claim 6 wherein said shaft is formedwith a plurality of passageways extending therethrough and opening intosaid chamber and further including a first electrical junction meanssecured to said shaft for rotation therewith and a second electricaljunction means secured to said housing, first electrical contact meansextending from said first junction means through said hollow shaft andthrough said passage means formed in said hollow shaft into said chamberto communicate between each rotary contact and the terminal of saidjunction means, and electrical conductor means extending coextensivelywith respect to said coil spring means to communicate between each ofsaid'oscillating contact means and a terminal of said junction carriedby said housing and additional electrical conductor means communicatingbetween electrical contacts of one of said rotary assemblies and thecorresponding electrical contact of the other of said rotary assemblieswhereby one electrical contact of each assembly is connected to a singleterminal of the rotary junction means.

12. A rotary electrical joint comprising:

a. at least one rotary electrical contact means adapted to be secured toa rotating member for rotation therewith about an axis,

b. at least one oscillating electrical contact means mounted formovement to and fro in a predetermined arc about said axis to cooperatewith said rotary contact to provide at least one pair of complementarycontacts consisting of a rotary contact and an oscillating contact,

c. means for maintaining said pair of complementary contacts inelectrical engagement during at least a portion of one revolution ofsaid rotary contacts,

d. circuit breaker means for cyclically moving said complementarycontacts away from one another in a direction substantially normal tothe direction of rotation of said contacts to disengage saidcomplementary contacts, and

e. return drive means driving said oscillating contact means in adirection opposite to the direction of rotation of said rotary contactmeans when disengaged from said rotary contact means by said circuitbreaker means.

13. A rotary electrical joint comprising:

a. at least two rotary electrical contact means adapted to be secured toa rotating member for rotation therewith about an axis,

b. at least two oscillating electrical contact means mounted formovement to and fro in a predetermined are about said axis independentlyof one another to cooperate with said rotary contacts to provide atleast two pairs of complementary contacts, each consisting of a rotarycontact and an oscillating contact,

c. means for maintaining each pair of contacts in electrical engagementduring at least a portion of one revolution of said rotary contacts,

d. circuit breaker means for cyclically disengaging one pair of contactswhile the other pair remains in contact and the second mentioned pair ofcontacts while the first mentioned pair of contacts remain in contact,said circuit breaker means including means for removing thecomplementary contacts of each pair of contacts away from one another ina direction substantially normal to the direction of rotation of saidcontacts to disengage the contacts while permitting slipping to occurbetween the contacts, return drive means for independently driving eachof said oscillating contact means in a direction opposite to thedirection of rotation of said rotary contact means when disengaged fromsaid rotary contact means by said circuit breaker means.

14. A rotary electrical joint for connecting two components, one ofwhich is to be mounted for rotation relative to the other, comprising:

a. a housing adapted to be secured to one of said components,

b. a chamber formed in said housing,

c. a hollow shaft rotatably mounted in said housing and extending intosaid chamber for rotation about a longitudinally extending axis,

d. at least two rotary contact assemblies mounted for rotation on saidshaft and spaced longitudinally relative to one another within saidchamber,

e. at least two oscillating electrical contact means mounted formovementto and fro within said housing relative to said shaft in a predeterminedare about said axis independently of one another, said oscillatingcontacts cooperating with said rotary contacts to provide at least twopairs of complementary contacts each consisting of a rotary contact andan oscillating contact, means for maintaining each pair of contacts inelectrical engagement during at least a portion of one revolution ofsaid rotary contacts,

f. circuit breaker means for cyclically disengaging one pair of contactswhile the other pair remains in contact and the second pair of contactswhile the first mentioned pair of contacts remain in contact, saidcircuit breaker means including means for moving the complementarycontacts of each pair of contacts away from one another in a directionsubstantially normal to the direction of rotation of said contacts todisengage the contacts while permitting slipping to occur between thecontacts,

g. return drive means for independently driving each of said oscillatingcontact means in a direction opposite to the direction of rotation ofsaid rotary contact means when disengaged from said rotary contact meansby said circuit breaker means.

15. A rotary electrical joint as claimed in claim 14 includingreleasable locking means for mechanically locking the contacts of eachpair of complementary contacts relative to one another to prevent rotaryslipping between the rotary contact and the oscillating contact of eachpair, said locking means being releasable by said circuit breaker meanswhen said complementary contacts of each pair of contacts are disengagedto permit the return drive means to operate.

16. A rotary electrical joint as claimed in claim 14 wherein said meansfor maintaining each pair of contacts in electrical engagement comprisesa pair of compression springs mounted coaxially with said shaft andreacting between said shaft and each of said electrical contact means.

17. A rotary electrical joint as claimed in claim 14 wherein said returndrive means comprises coil spring means connecting each of saidoscillating contact means to said housing, said coil spring means beingbiased to rotatably drive said oscillating assemblies in said directionopposite to the direction of rotation of the rotary contact means.

18. A rotary electrical joint as claimed in claim 17 including stopmeans coacting between said housing and each of said oscillating contactmeans to limit the rotation of said oscillating contact means in thedirection of rotation of said coil spring bias.

19. A rotary joint as claimed in claim 14 wherein each of said rotarycontact means is in the form of a contact assembly comprising:

a. a rotary contact support disc having a central passage therein toreceive said shaft, said disc being keyed to said shaft for longitudinalmovement relative to said shaft and rotation with said shaft,

b. a plurality of contact support rings mounted adjacent the outerperipheral edge of said rotary disc and arranged one on top of the otherin a direction towards the opposite ends of said housing, said rotarycontact support rings having inner peripheral edges spaced radiallyoutwardly from said shaft to form an annular contact chambertherebetween,

c. rotary electrical contacts extending radially inwardly from each ofsaid rotary contact support rings into said contact chamber, each ofsaid oscillating electrical contact means consisting of an assemblycomprising:

d. an oscillating contact support disc mounted on said shaft forrotation relative to said shaft about said axis and secured againstlongitudinal movement relative to said shaft,

e. a plurality of oscillating support rings mounted on said oscillatingsupport disc and extending longitudinally inwardly of said housing andoscillating electrical contacts extending radially outwardly from eachof said oscillating contact support rings, each of said oscillatingcontact assemblies being mounted for rotation about said shaft with saidoscillating contact support rings extending into a contact chamber of arotary contact assembly such that the radially extending electricalcontacts of the rotary assembly and the radially extending electricalcontacts of the oscillating assembly overlap one another.

20. A rotary joint as claimed in claim 19 wherein said circuit breakermeans comprises:

a. at least one cam roller mounted for rotation about a tions of theother cam surface such that said cam roller will displace one of saidrotary contact members longitudinally out of contact with itscomplementary oscillating transverse axis and fixed to said housing toextend into assembly when one of said protruding sections of said id hmbe 5 cam surface engages said roller means, and the other roeach ofsaid rotary support discs having an annular cam tary Contact will bemoved out of engagement with the t a k rfa e extending i a dl f h i hother oscillating assembly when the protruding sections edge thereof,said cam surfaces overlying said cam roller cam surface of the otherrotary assembly 15 8 8 means and having at least one protruding sectionextendy Salt} means P that 3 P other of h rotary t ins outwardly f theplane f the remainder f the cam 10 semblles will at all times remain incontact with an oscilsurface, the protruding sections of one cam surfacebeing latmg assembly' circumferentially spaced relative to theprotruding sec-

1. A rotary electrical joint comprising: a. at least one rotaryelectrical contact means adapted to be secured to a rotating member forrotation therewith about an axis, b. at least one oscillating electricalcontact means mounted for movement to and fro in a predetermined arcabout said axis to cooperate with said rotary contact to provide atleast one pair of complementary contacts consisting of a rotary contactand an oscillating contact, c. means for maintaining said pair ofcomplementary contacts in electrical engagement during at least aportion of one revolution of said rotary contacts, d. circuit breakermeans for cyclically disengaging said complementary contacts, e. returndrive means driving said oscillating contact means in a directionopposite to the direction of rotation of said rotary contact means whendisengaged from said rotary contact means by said circuit breaker means,and f. releasable locking means for mechanically locking saidcomplementaty contacts to one another to prevent slipping between therotary and oscillating contacts, said locking means being released bysaid circuit breaker when said complementary contacts are disengaged topermit the return drive means to operate.
 2. A rotary electrical jointcomprising: a. at least two rotary electrical contact means adapted tobe secured to a rotating member for rotation therewith about an axis, b.at least two oscillating electrical contact means mounted for movementto and fro in a predetermined arc about said axis independently of oneanother to cooperate with said rotary contacts to provide at least twopairs of complementary contacts, each consisting of a rotary contact andan oscillating contact, c. means for maintaining each pair of contactsin electrical engagement during at least a portion of one revolution ofsaid rotary contacts, d. circuit breaker means for cyclicallydisengaging one pair of contacts while the other pair remains in contactand the second mentioned pair of contacts while the first mentioned pairof contacts remain in contact, e. return drive means for independentlydriving each of said oscillating contact means in a direction oppositeto the direction of rotation of said rotary contact means whendisengaged from said rotary contact means by said circuit breaker means,and f. releasable locking means for mechanically locking the contacts ofeach pair of complementary contacts relative to one another to preventrotary slipping between the rotary contact and the oscillating contactof each pair, said locking means being releasable by said circuitbreaker means when said complementary contacts of each pair of contactsare disengaged to permit the return drive means to operate.
 3. A rotaryelectrical joint for connecting two components, one of which is to bemounted for rotation relative to the other, comprising: a. a housingadapted to be secured to one of said components, b. a chamber formed insaid housing, c. a hollow shaft rotatably mounted in said housing andextending into said chamber for rotation about a longitudinallyextending axis, d. at least two rotary contact assemblies mounted forrotation on said shaft and spaced longitudinally relative to one anotherwithin said chamber, e. at least two oscillating electrical contactmeans mounted for movement to and fro within said housing relative tosaid shaft in a predetermined arc about said axis independently of oneanother, said oscillating contacts cooperating with said roTary contactsto provide at least two pairs of complementary contacts each consistingof a rotary contact and an oscillating contact, means for maintainingeach pair of contacts in electrical engagement during at least a portionof one revolution of said rotary contacts, f. circuit breaker means forcyclically disengaging one pair of contacts while the other pair remainsin contact and the second pair of contacts while the first mentionedpair of contacts remain in contact, g. return drive means forindependently driving each of said oscillating contact means in adirection opposite to the direction of rotation of said rotary contactmeans when disengaged from said rotary contact means by said circuitbreaker means, and h. releasable locking means for mechanically lockingthe contacts of each pair of complementary contacts relative to oneanother to prevent rotary slipping between the rotary contact and theoscillating contact of each pair, said locking means being releasable bysaid circuit breaker means when said complementary contacts of each pairof contacts are disengaged to permit the return drive means to operate.4. A rotary electrical joint as claimed in claim 3 wherein saidreleasable locking means comprises latch means carried by each of saidrotary contacts and complementary slot means formed in each of saidoscillating contacts, said means for maintaining each pair of contactsin electrical engagement serving to urge said latch means intoengagement with said slot means.
 5. A rotary electrical joint as claimedin claim 3 wherein said means for maintaining each pair of contacts inelectrical engagement comprises a pair of compression springs mountedcoaxially with said shaft and reacting between said shaft and each ofsaid electrical contact means.
 6. A rotary electrical joint as claimedin claim 3 wherein said return drive means comprises coil spring meansconnecting each of said oscillating contact means to said housing, saidcoil spring means being biased to rotatably drive said oscillatingassemblies in said direction opposite to the direction of rotation ofthe rotary contact means.
 7. A rotary electrical joint as claimed inclaim 6 including stop means coacting between said housing and each ofsaid oscillating contact means to limit the rotation of said oscillatingcontact means in the direction of rotation of said coil spring bias. 8.A rotary joint as claimed in claim 3 wherein each of said rotary contactmeans is in the form of a contact assembly comprising: a. a rotarycontact support disc having a central passage therein to receive saidshaft, said disc being keyed to said shaft for longitudinal movementrelative to said shaft and rotation with said shaft, b. a plurality ofcontact support rings mounted adjacent the outer peripheral edge of saidrotary disc and arranged one on top of the other in a direction towardsthe opposite ends of said housing, said rotary contact support ringshaving inner peripheral edges spaced radially outwardly from said shaftto form an annular contact chamber therebetween, c. rotary electricalcontacts extending radially inwardly from each of said rotary contactsupport rings into said contact chamber, each of said oscillatingelectrical contact means consisting of an assembly comprising, d. anoscillating contact support disc mounted on said shaft for rotationrelative to said shaft about said axis and secured against longitudinalmovement relative to said shaft, e. a plurality of oscillating supportrings mounted on said oscillating support disc and extendinglongitudinally inwardly of said housing and oscillating electricalcontacts extending radially outwardly from each of said oscillatingcontact support rings, each of said oscillating contact assemblies beingmounted for rotation about said shaft with said oscillating contactsupport rings extending into a contact chamber of a rotary contactassembly such that the radially extending electrical contacts of therotAry assembly and the radially extending electrical contacts of theoscillating assembly overlap one another.
 9. A rotary joint as claimedin claim 8 wherein said circuit breaker means comprises: a. at least onecam roller mounted for rotation about a transverse axis and fixed tosaid housing to extend into said chamber, b. each of said rotary supportdiscs having an annular cam track surface extending inwardly from theperipheral edge thereof, said cam surfaces overlying said cam rollermeans and having at least one protruding section extending outwardlyfrom the plane of the remainder of the cam surface, the protrudingsections of one cam surface being circumferentially spaced relative tothe protruding sections of the other cam surface such that said camroller will displace one of said rotary contact members longitudinallyout of contact with its complementary oscillating assembly when one ofsaid protruding sections of said cam surface engages said roller means,and the other rotary contact will be moved out of engagement with theother oscillating assembly when the protruding sections of the camsurface of the other rotary assembly is engaged by said cam means suchthat one or other of the rotary assemblies will at all times remain incontact with an oscillating assembly.
 10. A rotary joint as claimed inclaim 3 including electrical conductor means for electrically connectingeach of the electrical contact means of one of the rotary contacts withan electrical contact means of the other rotary contact.
 11. A rotaryjoint as claimed in claim 6 wherein said shaft is formed with aplurality of passageways extending therethrough and opening into saidchamber and further including a first electrical junction means securedto said shaft for rotation therewith and a second electrical junctionmeans secured to said housing, first electrical contact means extendingfrom said first junction means through said hollow shaft and throughsaid passage means formed in said hollow shaft into said chamber tocommunicate between each rotary contact and the terminal of saidjunction means, and electrical conductor means extending coextensivelywith respect to said coil spring means to communicate between each ofsaid oscillating contact means and a terminal of said junction carriedby said housing and additional electrical conductor means communicatingbetween electrical contacts of one of said rotary assemblies and thecorresponding electrical contact of the other of said rotary assemblieswhereby one electrical contact of each assembly is connected to a singleterminal of the rotary junction means.
 12. A rotary electrical jointcomprising: a. at least one rotary electrical contact means adapted tobe secured to a rotating member for rotation therewith about an axis, b.at least one oscillating electrical contact means mounted for movementto and fro in a predetermined arc about said axis to cooperate with saidrotary contact to provide at least one pair of complementary contactsconsisting of a rotary contact and an oscillating contact, c. means formaintaining said pair of complementary contacts in electrical engagementduring at least a portion of one revolution of said rotary contacts, d.circuit breaker means for cyclically moving said complementary contactsaway from one another in a direction substantially normal to thedirection of rotation of said contacts to disengage said complementarycontacts, and e. return drive means driving said oscillating contactmeans in a direction opposite to the direction of rotation of saidrotary contact means when disengaged from said rotary contact means bysaid circuit breaker means.
 13. A rotary electrical joint comprising: a.at least two rotary electrical contact means adapted to be secured to arotating member for rotation therewith about an axis, b. at least twooscillating electrical contact means mounted for movement to and fro ina predetermined arc about said axis independently of one another tocooperate with said rotary contacts to provide at least two pairs ofcomplementary contacts, each consisting of a rotary contact and anoscillating contact, c. means for maintaining each pair of contacts inelectrical engagement during at least a portion of one revolution ofsaid rotary contacts, d. circuit breaker means for cyclicallydisengaging one pair of contacts while the other pair remains in contactand the second mentioned pair of contacts while the first mentioned pairof contacts remain in contact, said circuit breaker means includingmeans for removing the complementary contacts of each pair of contactsaway from one another in a direction substantially normal to thedirection of rotation of said contacts to disengage the contacts whilepermitting slipping to occur between the contacts, e. return drive meansfor independently driving each of said oscillating contact means in adirection opposite to the direction of rotation of said rotary contactmeans when disengaged from said rotary contact means by said circuitbreaker means.
 14. A rotary electrical joint for connecting twocomponents, one of which is to be mounted for rotation relative to theother, comprising: a. a housing adapted to be secured to one of saidcomponents, b. a chamber formed in said housing, c. a hollow shaftrotatably mounted in said housing and extending into said chamber forrotation about a longitudinally extending axis, d. at least two rotarycontact assemblies mounted for rotation on said shaft and spacedlongitudinally relative to one another within said chamber, e. at leasttwo oscillating electrical contact means mounted for movement to and frowithin said housing relative to said shaft in a predetermined arc aboutsaid axis independently of one another, said oscillating contactscooperating with said rotary contacts to provide at least two pairs ofcomplementary contacts each consisting of a rotary contact and anoscillating contact, means for maintaining each pair of contacts inelectrical engagement during at least a portion of one revolution ofsaid rotary contacts, f. circuit breaker means for cyclicallydisengaging one pair of contacts while the other pair remains in contactand the second pair of contacts while the first mentioned pair ofcontacts remain in contact, said circuit breaker means including meansfor moving the complementary contacts of each pair of contacts away fromone another in a direction substantially normal to the direction ofrotation of said contacts to disengage the contacts while permittingslipping to occur between the contacts, g. return drive means forindependently driving each of said oscillating contact means in adirection opposite to the direction of rotation of said rotary contactmeans when disengaged from said rotary contact means by said circuitbreaker means.
 15. A rotary electrical joint as claimed in claim 14including releasable locking means for mechanically locking the contactsof each pair of complementary contacts relative to one another toprevent rotary slipping between the rotary contact and the oscillatingcontact of each pair, said locking means being releasable by saidcircuit breaker means when said complementary contacts of each pair ofcontacts are disengaged to permit the return drive means to operate. 16.A rotary electrical joint as claimed in claim 14 wherein said means formaintaining each pair of contacts in electrical engagement comprises apair of compression springs mounted coaxially with said shaft andreacting between said shaft and each of said electrical contact means.17. A rotary electrical joint as claimed in claim 14 wherein said returndrive means comprises coil spring means connecting each of saidoscillating contact means to said housing, said coil spring means beingbiased to rotatably drive said oscillating assemblies in said directionopposite to the direction of rotation of the rotary contact means.
 18. Arotary electrical joInt as claimed in claim 17 including stop meanscoacting between said housing and each of said oscillating contact meansto limit the rotation of said oscillating contact means in the directionof rotation of said coil spring bias.
 19. A rotary joint as claimed inclaim 14 wherein each of said rotary contact means is in the form of acontact assembly comprising: a. a rotary contact support disc having acentral passage therein to receive said shaft, said disc being keyed tosaid shaft for longitudinal movement relative to said shaft and rotationwith said shaft, b. a plurality of contact support rings mountedadjacent the outer peripheral edge of said rotary disc and arranged oneon top of the other in a direction towards the opposite ends of saidhousing, said rotary contact support rings having inner peripheral edgesspaced radially outwardly from said shaft to form an annular contactchamber therebetween, c. rotary electrical contacts extending radiallyinwardly from each of said rotary contact support rings into saidcontact chamber, each of said oscillating electrical contact meansconsisting of an assembly comprising: d. an oscillating contact supportdisc mounted on said shaft for rotation relative to said shaft aboutsaid axis and secured against longitudinal movement relative to saidshaft, e. a plurality of oscillating support rings mounted on saidoscillating support disc and extending longitudinally inwardly of saidhousing and oscillating electrical contacts extending radially outwardlyfrom each of said oscillating contact support rings, each of saidoscillating contact assemblies being mounted for rotation about saidshaft with said oscillating contact support rings extending into acontact chamber of a rotary contact assembly such that the radiallyextending electrical contacts of the rotary assembly and the radiallyextending electrical contacts of the oscillating assembly overlap oneanother.
 20. A rotary joint as claimed in claim 19 wherein said circuitbreaker means comprises: a. at least one cam roller mounted for rotationabout a transverse axis and fixed to said housing to extend into saidchamber, b. each of said rotary support discs having an annular camtrack surface extending inwardly from the peripheral edge thereof, saidcam surfaces overlying said cam roller means and having at least oneprotruding section extending outwardly from the plane of the remainderof the cam surface, the protruding sections of one cam surface beingcircumferentially spaced relative to the protruding sections of theother cam surface such that said cam roller will displace one of saidrotary contact members longitudinally out of contact with itscomplementary oscillating assembly when one of said protruding sectionsof said cam surface engages said roller means, and the other rotarycontact will be moved out of engagement with the other oscillatingassembly when the protruding sections of the cam surface of the otherrotary assembly is engaged by said cam means such that one or other ofthe rotary assemblies will at all times remain in contact with anoscillating assembly.